Servomechanism



1958 D. R. LAMBERT 2,845,801

SERVOMECHANISM Filed March 16, 1956 United States Patent 2,845,804SERVOMECHANISM Donald Rudolf Lambert, Carshalton, England, assignor toPowers-Samas Accounting Machines Limited, London, England, a Britishcompany Application March 16, 1956, Serial No. 572,147 Claims priority,application Great Britain May 4, 1955 1 Claim. (Cl. 74110) Thisinvention relates to a servomechanism to control a relatively powerfulmechanical movement by the use of a small stationary electro-magnetwhich, due to its low power supply, cannot of itself be employed to dothe work.

According to the present invention there is provided a servomechanismcomprising a reciprocable driving member, a motion-transmitter pivotedon the driving member for movement therewith and resiliently urged to aninactive position thereof, and an electro-magnet having an armatureoperable on energization of the electro-magnet to elfect pivoting of themotion-transmitter to the active position thereof thereby to positionthe motion-transmitter to transmit motion imparted thereto by thedriving member.

In order that the invention may be clearly understood one embodimentthereof will now be described, by way of example, with reference to theaccompanying diagrammatic drawings in which:

Figure l is an elevation, partly in section, of servomechanism accordingto the invention, and

Figures 2 and 3 are views similar to Figure 1 but with the parts shownin different positions thereof.

Referring to the drawings a driving member 1 is supported forreciprocation, as indicated by the doubleheaded arrow, by any suitablemeans not shown. A motion-transmitter formed by a rocking bar 2 ispivoted at 3 to the driving member for movement therewith and a spring 4is arranged resiliently to urge the motiontransmitter to the inactiveposition thereof illustrated in Figs. 1 and 3.

As illustrated in Fig. 1 the driving member is in the starting positionthereof, and, when in this position, it engages a spring 5 whichco-operates with an armature 6 pivoted at 7 to a small stationaryelectro-magnet 8 and presses the armature into the active positionthereof at which the upper overturned end 9 of the armature is locatedin a notch 10 formed in the under side of the motion-transmitter 2. Theelectro-magnet 8 is included in an electric circuit 11 and is controlledby a switch 12 which may be manually operated or which can bemechanically or electrically operated as desired.

The motion-transmitter 2 is arranged to transmit motion imparted theretoby the driving member 1 to a bar 13 mounted for lengthwise slidingmovement in guides 14, 15. The bar 13, on lengthwise movement thereof,may be arranged to operate any desired mechanism, as for example amultiple switch, a tripping or a setting mechanism' As can be seen fromthe drawings the bar 13 is provided with a notch 16 to be engaged by thenose 17 of the motion-transmitter 2 when this part is in the activeposition as shown in Fig. 2.

Fig. 2 illustrates the fully forward position of the driving member 1with the motion-transmitter 2 in the active position thereof andillustrates the manner in which the motion transmitted to themotion-transmitter is imparted to the bar 13 to effect lengthwisemovement thereof. From Fig. 2 it will be noted that the switch 12 is inthe close Position thereof so that the armature 6 is re ed n i s act p si n bythe electrom t 8 and the switch 12 is closed before commencementof the fcrwardmq m nt, that i mo emen t h left as viewed i he ra ings, fhedriving mem e n e the armature 6 is retained in its active position,as the d iv ng m be 1 moves o the left, as. vi wed n the drawings, themotion-transmitter 2 rides over the overturned portion 9 of the armaturebeing thereby turned counter-clockwise about its pivot 3 against theaction of spring 4. The underside of the motion-transmitter 2 restsagainst the top of the overturned portion 9 and during the forwardmovement of the driving member 1, the nose 17 engages in the notch 16 sothat the continued forward movement of the driving member 1 and motiontranlsmitter 2 causes the slide 13 to be moved to the left, as viewed inthe drawings. The slide 13 can be restored by any suitable means, notshown, as for example by a spring or by a positively operated restoringmember. On return movement of the driving member 1 to the startingposition thereof, the motiontransmitter again rides over the overturnedportion 9 until the portion 9 of the armature enters the notch 10 whenthe spring 4 will restore the motion-transmitter 2 to the inactiveposition thereof.

In the event that, when the driving member commences its forwardmovement, the switch 12 remains open, as shown in Fig. 3, so that theelectromagnet is not energized, the spring 4 is sufficiently strong toensure that the armature 6 is moved counter-clockwise about its pivot 7by the forward movement of the motiontransmitter 2 together with thedriving member. During such forward movement, the spring 4 urges themotion-transmitter 2 into engagement with an abument, illustrated as apin 18, extending laterally from the driving member. Thus, when theele'ctro-magnet 8 is not energized, the motion-transmitter 2 remains inthe inactive position thereof, as illustrated in Fig. 3, and the nose 17of the motion-transmitter is retained in a position at which it is notengaged in the notch 16 but passes over the top of the slide 13 which,accordingly, is not moved lengthwise during this operation of thedriving member 1. From Fig. 3 it will be noted that, during the forwardmovement of the driving member 1, the spring 5 is disengaged by thedriving member, but on the return movement of the driving member thespring 5 is again engaged thereby so that the driving member 1 restoresthe armature 6 to the active position thereof illustrated in Fig. 1, inwhich the overturned end of the armature is again located in the notch10.

In the foregoing description there has been described the provision ofonly one motion-transmitter on the driving member 1, but it is to beunderstood that a plurality of motion-transmitters can be supported bythe driving member 1, each for control by an electro-magnet 8 to operatea slide 13 appropriated thereto. Thus, by selective operation of theswitches 12, the slides 13 will be appropriately operated and by such amultiple relay a plurality of mechanisms can be selectively controlled.The servomechanism herein described is found to be particularly suitablefor use in record controlled statistical machines in which control ofrelatively powerful mechanical movements is to be effected by anelectrical signal the strength of which is, of itself, sufiicient onlyto effect energization of a small stationary electro-magnet.

I claim:

A servomechanism comprising a reciprocable driving member, amotion-transmitter pivoted on the driving member for movement therewith,a spring urging the motion transmitter about its pivot to an inactiveposi- 3 tion thereof in which it is arrested by an abutment carried bythe driving member, and an electro-magnet the armature of which isadapted on energization of the electro-magnet to effect rotation of themotion-transmitter about its pivot to the active position thereof,characterized in that the armature is pivoted to the electro-magnet andin the starting portion of the driving member is retained in activerelation with the electromagnet by a second spring co-operating with thearmature and engaged by the driving member to locate an end portion ofthe armature in a notch formed in the motiontransmitter, the arrangementbeing such that the armature is retained in its active position andeffects rotation of the motion-transmitter if the electro-magnetReferences Cited in the file of this patent UNITED STATES PATENTS2,225,252 Auld et a1. Dec. 17, 1940

